This invention relates to the moulding of composite materials and in particular to the moulding of composite materials comprising reinforcing filaments enclosed in a resin matrix.
It is known to manufacture components by moulding composite materials using what is commonly known as the rubber expansion method. In one version of that method, layers of filaments which have been pre-impregnated with a resin binder are laid-up in a suitably shaped former and covered by an appropriately shaped silicone rubber member. The rubber member is covered in turn by a suitable rigid member so that as the whole assembly is heated, the silicone rubber expands to exert pressure upon the prepregs so that they conform to the shape of the former, consolidate and the resin, if it is a thermosetting resin, cures.
The silicone rubber expansion method of moulding is effective in the moulding of composite materials having a resin matrix material which flows and cures at temperatures around 200.degree. C. However, if the resin matrix material flows and cures at higher temperatues, for instance temperatures of about 250.degree. C. and upwards in the case of polyimides, the silicone rubber thermally degrades to such an extent that it is not re-usable.
It is an object of the present invention to provide a method of moulding composite materials in which the problems associated with expansion moulding utilizing silicone rubber at higher temperatures are substantially avoided.